LED lamp

ABSTRACT

An LED lamp includes LED chips, an axle, and a lampshade. The LED chips are mounted on surface of the axle. The axle which is coupled to the lampshade includes heat pipes for transferring the heat generated by the LED chips to exterior of the lampshade and obtaining a better heat dissipation.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of parent application Ser. No. 10/963,401, filedOct. 12, 2004 now U.S. Pat. No. 7,314,291. The entire disclosure of theparent application is incorporated herein by reference.

FIELD OF THE INVENTION

The invention generally relates to an LED lamp, and in particularrelates to an LED lamp applying heat pipe for heat dissipation.

BACKGROUND OF THE INVENTION

Light emitting diode (LED) is a highly efficient device to transformelectric energy into light in comparison to conventional incandescentbulbs. The most important part of an LED is the semi-conductor chiplocated in the center of the bulb. The LED chip has two regionsseparated by a junction. The p region is dominated by positive electriccharges, and the n region is dominated by negative electric charges. Thejunction acts as a barrier to the flow of electrons between the p andthe n regions. Only when sufficient voltage is applied to thesemi-conductor chip, can the current flow, and the electrons cross thejunction into the p region. When an electron moves sufficiently close toa positive charge in the p region, the two charges “re-combine”. Eachtime an electron recombines with a positive charge, electric potentialenergy is converted into electromagnetic energy. For each recombinationof a negative and a positive charge, a quantum of electromagnetic energyis emitted in the form of a photon of light.

LEDs have advantages of small size, low driving voltage, fast response,resistance to vibration and long service life. They do dozens ofdifferent jobs and are found in all kinds of devices. Among otherthings, they form the numbers on digital clocks, transmit informationfrom remote controls, light up watches and tell you when your appliancesare turned on. Collected together, they can form images on a jumbotelevision screen or illuminate a traffic light.

Common LED lamps usually can be divided into two kinds of monochromaticlight and polychromatic light. The polychromatic light LED lamp usuallyincludes several lamps being able to provide different colored lightsunder individual controls so as to perform blends of light change.

As shown in FIG. 1, a side view of an LED lamp unit disclosed in U.S.Pat. No. 6,577,073, a lamp unit 1000 mainly includes LED lamps 100, areflector 110 and a power supply 120. The reflector 110 reflects thelight produced from the LED lamps 100. The power supply 120 suppliespower to the lamps 100. A number of, typically 10 to 200, LED lamps 100are arranged on the bottom of the reflector 110 to provide the requiredluminosity. As shown in FIG. 2, each LED lamp includes blue and red LEDsand a phosphor. The blue LED produces an emission at a wavelengthfalling within a blue wavelength range. The red LED produces an emissionat a wavelength falling within a red wavelength range. The phosphor isphotoexcited by the emission of the blue LED to exhibit a luminescencehaving an emission spectrum in an intermediate wavelength range betweenthe blue and red wavelength ranges.

In each LED lamp 100, the blue and red LEDs and the phosphor areintegrated together within a single envelope. The lamp unit 1000 iscomposed of a plurality of such LED lamps. In comparison with prior artsthat individual LED of monochromatic light being used, the LED lamp 100of the prior patent saves about half of the space and cost of package.

However, in FIG. 1, the whole assembly of the plurality of LED lamps 100in envelopes still occupies much area and decreases the number ofpossible LED lamps in the cluster and the luminosity of the lamp unit1000 in the limited space.

There is further a problem that when arranging the LED lamps 100 tightlyto get higher luminosity, the heat generated from the LED lamps is hardto be dissipated. The reflector 110 thermally coupled through solidconduction to the LED lamps 100 is insufficient for dissipating theheat. The heat accumulation will influence the service life of the lampunit 1000.

SUMMARY OF THE INVENTION

In view of the aforesaid problems, the invention provides an LED lampapplicable to spotlight, headlight, house lamp, street lamp and so on.The LED lamp mainly includes a lampshade, an axle, LED chips, a drivingcircuit and a heat pipe.

The lampshade can be a bowl-shaped structure having a concave surface, acentral hole and an opening. The surface can be used to reflect thelight emitted from the LED chips. To achieve a better reflection, thesurface is coated with a reflective film of suitable material.

The central hole is formed on bottom of the lampshade for receiving theaxle and the heat pipe passing through. This heat pipe protrudes acrossboth sides of the lampshade. A transparent plate is formed on theopening of the lampshade for enabling the light to pass through whilepreventing dust, insect or the like entering the lampshade andinfluencing the service life of the LED chips.

The material of the axle can be chosen from general printed circuitboards, ceramics or other electrically insulative while thermallyconductive material. The heat pipe passes the central hole into thelampshade, and being defined with a heat receiving portion and a heatdissipation portion. The heat receiving portion is covered by thelampshade where the LED chips emit light and heat.

Several LED chips are mounted on surface of the axle and correspondingto the heat receiving portion of the heat pipe, including the exterioraxial surface of the axle and the end surface facing the transparentplate. The color, number and arrangement of the LED chips can bedesigned by user for achieving specific light effects.

The characteristics of the invention are that the LED chips can be barechips without packages as prior arts. Therefore, the quantity of LEDchips capable of being arranged in the limited area can be increased soas to increase the luminosity. Meanwhile, the cost and time of packagingthe LED chips individually are also saved.

The driving circuit is embedded in the axle for actuating the LED chipsindividually, controlling the brightness and color blending of the LEDlamp, and preventing static electricity to damage the LED chips. The LEDchips are electrically connected to the driving circuit throughembedding, wire bonding or other methods.

The heat pipe is installed along the axle for dissipating the heatgenerated by the LED chips from the heat receiving portion to the heatdissipation portion. The heat pipe is able to transport heat by anevaporation-condensation cycle with the help of porous capillaries. Itdissipates the heat at the heat dissipation portion via naturalconvection or additional cooling fan, and solves the problem of heataccumulation in the LED chips.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more fully understood from the detaileddescription given hereinbelow. However, this description is for purposesof illustration only, and thus is not limitative of the invention,wherein:

FIG. 1 is a side view of an LED lamp unit disclosed in U.S. Pat. No.6,577,073;

FIG. 2 is a side view of an LED lamp used in a lamp unit of U.S. Pat.No. 6,577,073;

FIGS. 3A and 3B are side view and front view of an LED lamp of a firstembodiment of the invention;

FIG. 4 is a sectional view of a pyramid lampshade in an LED lamp of theinvention;

FIG. 5 is a front view of a polygon axle in an LED lamp of theinvention;

FIG. 6 is a front view of an axle where LED chips are dispersedlyarranged;

FIG. 7 is a side view of an LED lamp of a second embodiment of theinvention;

FIG. 8 is a side view of an LED lamp of a third embodiment of theinvention;

FIG. 9 is a side view of an LED lamp of a fourth embodiment of theinvention;

FIG. 10 is a side view of an LED lamp of a fifth embodiment of theinvention;

FIG. 11 is a front view of an LED lamp of a sixth embodiment of theinvention;

FIGS. 12A and 12B are side view and front view of an LED lamp of aseventh embodiment of the invention;

FIG. 13 is a front view of four quarters of circular heat pipes of anLED lamp of the invention; and

FIG. 14 is a sectional front view of an axle that includes a core.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 3A and 3B, a side view and a front view of an LED lampin a first embodiment of the invention, the LED lamp 200 mainly includesa lampshade 210, an axle 220, LED chips 230, a driving circuit (notshown) and a heat pipe 240.

The lampshade 210 is a bowl-shaped construction having a concave surface211, a central hole 212 and an opening 213. The concave surface 211 isused to reflect the light emitted from the LED chips 230 toward theopening 213 of the lampshade 210. To achieve a better reflection, thesurface 211 is coated with a reflective film of suitable material or hasbeen polished to reflect light. The central hole 212 is formed on bottomof the lampshade 210 for receiving the axle 220 and the heat pipe 240passing through.

A transparent plate 250 is mounted on the opening 213 of the lampshade210 for enabling the light emitted from the LED chips 230 to passthrough while preventing dust, insect or the like entering the lampshade210 and influencing the service life of the LED chips 230. Thetransparent plate 250 can also be processed with diffusion patterns,light-enhancing film, polarization film and so on for achievingdifferent light effects.

The shape of the lampshade 210 is not limited to spherical but also be apyramid as shown in FIG. 4, or other concave shapes.

The axle 220 passes the central hole 212 and extrudes into the lampshade210. The material of the axle 220 can be chosen from general printedcircuit boards, ceramics or other electrically insulative whilethermally conductive material.

The heat pipe 240 passes the central hole into the lampshade 210 andbeing defined with a heat receiving portion 241 (at the left side of thedrawing) and a heat dissipation portion 242 (at the right side ofdrawing). The heat receiving portion 241 is covered by the lampshade 210where the LED chips 230 emit light and heat.

Several LED chips 230 are mounted on surface of the axle 220 andcorresponding to the heat receiving portion 241 of the heat pipe 240,including the exterior axial surface 221 of the axle 220 and the endsurface 222 facing the transparent plate 250.

The driving circuit (not shown in the drawing) is embedded in the axle220 for activating the LED chips 230 individually, controlling thebrightness and color blending of the LED lamp 200, and preventing staticelectricity to damage the LED chips 230. The LED chips 230 areelectrically connected to the driving circuit through embedding, wirebonding or other methods.

When using printed circuit board to make the axle 220, the drivingcircuit can be made with stacks inside the axle 220, or printed onsurface of the axle 220. When the axle 220 is not made by printedcircuit board, the surface of the axle 220 can be covered with a printedcircuit to achieve the same function.

In order to prevent oxidization of the LED chips 230 caused by directexposure to the air, the space enclosed by the lampshade 210 and thetransparent plate 250 can be filled with nitrogen or other inert gas.Or, the surface of the LED chips 230 is coated with a transparentmaterial, such as epoxy or silicone. Another method is to vacuum thespace enclosed by the lampshade 210 and the transparent plate 250 and toprevent the LED chips 230 from reaction with air.

The characteristics of the invention are that the LED chips 230 are barechips without packages as prior arts. Therefore, the quantity of LEDchips 230 capable of being arranged in the limited area can be increasedso as to increase the luminosity. Meanwhile, the cost and time ofpackaging the LED chips 230 individually are also saved so as to improvethe manufacturing efficiency of the LED lamp 200.

The LED chips 230 mounted on the axle 220 can be of monochromic light orpolychromatic light. When using LED chips 230 of different colors, thedifferent color LED chips 230 (for example of red, blue and greenlights) are interposed so that the adjacent LED chips 230 can becontrolled to provide different colors of light for different lighteffects of the LED lamp 200.

The heat pipe 240 is installed along the axle 220 for dissipating theheat generated by the LED chips 230 from the heat receiving portion 241to the heat dissipation portion 242. The heat pipe 240 is able totransport heat by an evaporation-condensation cycle with the help ofporous capillaries. It dissipates the heat at the heat dissipationportion 242 via natural convection or an additional cooling fan 260, andsolves the problem of heat accumulation in the LED chips 230.

The heat pipe 240 works with liquid and gas phase transitions of aworking fluid sealed inside the heat pipe. It has a thermalconductibility dozens of times to that of copper. Therefore, the heatapplied to the heat receiving portion 241 of the heat pipe 240 is fasttransferred to the heat dissipation portion 242.

The section of the axle 220 is not limited to circular as shown in FIG.3B, but can also be polygons as shown in FIG. 5, or any other suitableshape.

The arrangement of the LED chips 230 on the axle 220 can be tight asshown in FIG. 3B, or be dispersed as shown in FIG. 6 for different lighteffects.

Now referring to FIG. 7, a second embodiment of the invention, the LEDlamp is similar to the first embodiment but having radiation fins 270mounted on the end of heat pipe 240 for dissipating the heat transferredto the heat dissipating portion 242. In accompany with an additional fan260 to expel airflow, higher efficiency heat dissipation is achieved.

The LED chips 230 can be of monochromic light or polychromatic light.When using LED chips 230 of different colors, the different color LEDchips 230 (for example of red, blue and green lights) are interposed sothat the adjacent LED chips 230 can be controlled to provide differentcolors of light for different light effects of the LED lamp. Thearrangement of the LED chips can be tight or dispersed.

As shown in FIG. 8, the heat pipe 240 is replaced with several heatpipes 243 of smaller dimensions to get the same function.

FIG. 9 is a side view of an LED lamp of a fourth embodiment of theinvention. The LED lamp is similar to the first embodiment but the heatpipe 240 of FIG. 3 being replaced with a thermally conductive rod (suchas a copper rod) 280 for dissipating the heat transferred from the heatreceiving portion 241 to the heat dissipating portion 242. Similarly,several radiations fins 270 can be mounted on the end of the rod 280 toobtain higher efficiency heat dissipation.

The LED chips 230 can be of monochromic light or polychromatic light.When using LED chips 230 of different colors, the different color LEDchips 230 (for example of red, blue and green lights) are interposed sothat the adjacent LED chips 230 can be controlled to provide differentcolors of light for different light effects of the LED lamp. Thearrangement of the LED chips can be tight or dispersed.

FIG. 10 is a side view of an LED lamp of a fifth embodiment of theinvention. The LED lamp is similar to the fourth embodiment but having aplurality of small passages formed in parallel in the thermallyconductive rod 280 and allowing fluid to flow inside of the passages forheat transfer purpose. The fluid can be gas or liquid for transferringthe heat from the heat receiving portion 241 to the heat dissipatingportion 242.

The LED chips 230 can be of monochromic light or polychromatic light.When using LED chips 230 of different colors, the different color LEDchips 230 (for example of red, blue and green lights) are interposed sothat the adjacent LED chips 230 can be controlled to provide differentcolors of light for different light effects of the LED lamp. Thearrangement of the LED chips can be tight or dispersed.

FIG. 11 is a front view of an LED lamp of a sixth embodiment of theinvention. The LED lamp 200 is simplified from the first embodiment. Aninsulation layer 290 is formed outside the heat pipe 240 for the LEDchips 230 to be mounted on. The arrangement of the LED chips can betight or dispersed.

The LED chips 230 can be of monochromic light or polychromatic light.When using LED chips 230 of different colors, the different color LEDchips 230 (for example of red, blue and green lights) are interposed sothat the adjacent LED chips 230 can be controlled to provide differentcolors of light for different light effects of the LED lamp. Thearrangement of the LED chips can be tight or dispersed.

FIGS. 12A and 12B are side view and front view of an LED lamp of aseventh embodiment of the invention. The axle 300 has a differentconstruction from the aforesaid embodiments. The axle 300 is composed ofeight heat pipes 301 each having a trapezoid section so as to form theaxle 300 an octagon section with a hollow core. An end plate 330 ismounted on front end of the axle 300 and facing the transparent cover250.

Of course, the heat pipes 301 of the axle 300 are not limited to theoctagon section. They can be of quarters of a circle as shown in FIG.13, or other sections to form an axle 300 with circular, hexagon orother polygon sections.

A fluid conduit 3011 is formed inside each heat pipe 301 for performingliquid and gas phase cycles and removing the heat from the LED chips230. The exterior surface 3012 of each heat pipe 301 is covered with alayer of printed circuit board 310. The driving circuit (not shown inthe drawing) is stacked in the printed circuit board 310, or printed onsurface of the printed circuit board 310.

Further, the printed circuit board 310 on exterior surface 3012 of theheat pipe 301 can be replaced with an insulation layer, such as an oxideor ceramic material to get the same insulation function. Then, formingthe driving circuit inside or on surface of the insulation layer.

The axle 300 passes the central hole 212 and extrudes into the lampshade210. Each heat pipe 301 passes the central hole 212 into the lampshade210, and being defined with a heat receiving portion 302 and a heatdissipation portion 303. As shown in FIG. 14, a rod 320 is inserted intothe axle 300 for improving the stiffness of the axle 300.

The LED chips 230 are mounted on the exterior surface 3012 of the heatpipes 301 and the end plate 330. The LED chips 230 can be of monochromiclight or polychromatic light. When using LED chips 230 of differentcolors, the different color LED chips 230 (for example of red, blue andgreen lights) are interposed so that the adjacent LED chips 230 can becontrolled to provide different colors of light for different lighteffects of the LED lamp. The arrangement of the LED chips can be tightor dispersed.

The heat generated by the LED chips 230 is transferred from the heatreceiving portion 302 to the heat dissipating portion 303 by means ofthermal conduction of each heat pipe 301. The heat transferred to theheat dissipation portion 242 is then dissipated by natural convection oran additional cooling fan 260. It solves the problem of heataccumulation in the exterior surface 3012 of the heat pipe 301.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

1. An LED lamp, comprising: a lampshade having a concave surface, atleast a hole and an opening said hole being formed on said lampshade; anaxle including a plurality of heat pipes, each one of said heat pipeshaving a heat receiving portion being coupled to said lampshade and aheat dissipating portion being disposed outside of said lampshade; and aplurality of LED chips, mounted on surface of said heat receivingportion of said heat pipes; wherein said plurality of LED chips and saidheat pipes are arranged with respect to each other so that heatgenerated by said LED chips is transferred by said heat pipes from saidheat receiving portion to said heat dissipating portion.
 2. The LED lampaccording to claim 1, wherein surface of said LED chips are covered witha transparent material for preventing said LED chips from reaction withair.
 3. The LED lamp according to claim 2, wherein said transparentmaterial is chosen from one of epoxy and silicone.
 4. The LED lampaccording to claim 1, further comprising a transparent plate mounted onsaid opening of said lampshade for preventing foreign objects enteringsaid lampshade.
 5. The LED lamp according to claim 4, wherein a spaceenclosed by said transparent plate and said lampshade is filled with atransparent material for preventing said LED chips from reaction withair.
 6. The LED lamp according to claim 5, wherein said transparentmaterial is chosen from one of nitrogen and inert gas.
 7. The LED lampaccording to claim 5, wherein said transparent material is chosen fromone of epoxy and silicone.
 8. The LED lamp according to claim 4, whereina space enclosed by said transparent plate and said lampshade isvacuumed for preventing said LED chips from reaction with air.
 9. TheLED lamp according to claim 1, wherein an end of said axle is coveredwith an end plate for mounting LED chips.
 10. The LED lamp according toclaim 1, wherein each heat pipe has a trapezoid section for forming saidaxle with a polygon section.
 11. The LED lamp according to claim 1,wherein each exterior surface of said heat pipe is covered by a printedcircuit board.
 12. The LED lamp according to claim 1, further comprisingan electrically insulation layer covering exterior surface of said heatpipes.
 13. The LED lamp according to claim 1, wherein said LED chips arebare chips.
 14. The LED lamp according to claim 1, wherein said LEDchips emit light of different colors or the same color.
 15. The LED lampaccording to claim 1, wherein said axle further comprises a rod forenhancing stiffness.
 16. The LED lamp according to claim 1, furthercomprising at least a radiation fin mounted on said heat dissipatingportion of said axle.
 17. The LED lamp according to claim 1, whereinsaid heat pipes pass through said hole into said lampshade, extendacross both sides of said lampshade and is defined with said heatreceiving portion and said heat dissipating portion.
 18. The LED lampaccording to claim 1, wherein said heat receiving portion is disposedinside of said lampshade.
 19. An LED lamp, comprising: a lampshadehaving a reflective surface and a hole formed therein; an axle extendingthrough the hole and including one or more heat transfer members,wherein each one of the heat transfer members has a heat receivingportion coupled to the lampshade and a heat dissipating portion locatedoutside of the lampshade; and a plurality of LED chips mounted on theheat receiving portions of the one or more heat transfer members;wherein the plurality of LED chips and the one or more heat transfermembers are arranged with respect to each other such that heat,generated by the LED chips is transferred by the one or more heattransfer members from the heat receiving portions to the heatdissipating portions.
 20. The LED lamp of claim 19, wherein thereflective surface has a concave-shaped sectional side profile.
 21. TheLED lamp of claim 19, wherein the reflective surface has apyramid-shaped sectional side profile.
 22. The LED lamp of claim 19,wherein the one or more heat transfer members comprises one or more heatpipes.